So poking around in my dash last night I see two female antenna plugs. After some forum searching & noticing the top of the hatch, I guess our cars have two antennas: the aerial & hatch antenna. This leads me to my question. Has anyone had success hooking an aftermarket radio to ONLY the hatch antenna? I can't stand the look of my car with the aerial up, its huge. Furthermore is there an easy way to distinguish which plug goes to which antenna?

 

Hmm I only have 1 male antenna plug in my 93.

 

I have what the OP describes. Two antenna leads. But the stock antenna doesn't bother me...I can't see it from the driver's seat.
Depending on your area, I doubt the hatch lead alone will give very good/consistent reception. Probably better off installing a stubby. Or if you're dead-set on smoothing the hole, maybe install/leave the antenna behind the rear hatch plastic somewhere.

 

There've been a couple of threads on this in the past. The hatch-glass antenna seems to pull in one frequency better whilst the regular mast antenna does the same on other frequencies.
Or so I seem to remember.

Both my 2012 Mazda 6 and 2013 Mazda 3 have the hatch antenna only, and they work phenomenally well...

As for the FD, I personally like having all the original bits present and functioning.

 

The hatch antenna favors horizontal polarization and tends to be directional (as it is a dipole of sorts) favoring signals along the car's major axis. (Not unlike the infamous GM windshield antennas of the '70's)

The main antenna is vertically polarized and is relatively non-directional. Note that the main antenna has a preamp built into the base, no doubt an important part of the performance equation.

I have tried to use the hatch antenna in lieu of the main antenna with relatively poor results. I can't speak to the tuning or bandwidth of either antenna, as I haven't swept them--but I expect that they are broad and flat enough to provide reasonable performance across the FM band.

The diversity system is designed to take advantage of the instantaneous differences in signal phase and amplitude at the antennas to help mitigate multipath interference. The hatch antenna is intended to provide backup--the short story being that there is a high probability that there will be a useable signal at the hatch antenna at any point in space and time when the main antenna encounters a 'null'.

 

Quality information. Thank you sir.

I want to keep all the factory function on the car, not going to fill the antenna hole. I hardly listen to radio anymore and that antenna is just god awful in rolling shots. My aftermarket radio extends the antenna as soon as its turned on (CDs & MP3s). I guess I will install a dip switch for antenna control & use a splitter like this to take advantage of both antennas

 

Some detailed updates:

So the hatch antenna uses a smaller style plug, easy way to tell the difference. The above splitter will not work. The radio reception is absolutely null when the aerial is fully retracted. Switch installed in my din plate, clean & still functional.

 

Sounds like you've accomplished your goal.